Towing vehicle for maneuvering aircraft

ABSTRACT

In a towing vehicle (1) for manoeuvring aircraft (11) without a towbar, the chassis (5) of which vehicle has a fork-like receiving area (7) between the wheels (6) of a coaxial wheel suspension, in which receiving area there is arranged a retractable and extensible gripping and drawing-in device (9) which is fastened to a lifting blade (8) and by means of which the nosewheel (10) of an aircraft (11) can be gripped and drawn onto the lifting blade (8) which is pivotable relative to the chassis (5) both about a transverse axis and, for matching to oblique positions of a nosewheel (10) which has been received, about a longitudinal axis by means of two fluid piston-cylinder units (12) arranged symmetrically relative to one another between the chassis (5) and the lifting blade (8), the lifting blade (8) is coupled so as to be pivotable in all directions by means of a ball joint (25) which is fastened to the chassis (5) of the towing vehicle (1) and acts centrally on the back of the lifting blade (8). Furthermore at least one fluid piston-cylinder unit (12), acting on the lifting blade (8) above or below the ball joint (25) at a distance from the latter, can be locked and released in a position which raises the lifting blade (8).

The invention relates to a towing vehicle for maneuvering aircraftwithout a towbar, the chassis of which vehicle has a fork-like receivingarea between the wheels of a wheel axle, in which receiving area thereis arranged a retractable and extensible gripping and drawing-in devicewhich is fastened to a lifting blade and by means of which the nosewheelof an aircraft can be gripped and drawn onto the lifting blade which ispivotable relative to the chassis both about a transverse axis and, formatching to oblique positions of a nosewheel which as been received,about a longitudinal axis by means of two fluid piston-cylinder unitsarranged symmetrically relative to one another between the chassis andthe lifting blade.

A towing vehicle of this design is known (DE-A 38 01 855), in which thelifting blade is arranged on the chassis in such a way that it can beraised, lowered and optionally tilted onto an angular position by meansof lower and upper longitudinal coupling rods and can be actuated bymeans of fluid piston-cylinder units, the upper and lower longitudinalcoupling rods forming a linkage which is coupled at one end to thechassis and at the other end to the blade. In order to allow the liftingblade to adapt automatically to any inclination of the nosewheel, thedirections in which the upper longitudinal coupling rods act shouldintersect on an imaginary longitudinal axis at a point forming apendulum point of the lifting blade. In this case, the longitudinalcoupling rods can be designed as fluid piston-cylinder units which areconnected to one another in a communicating manner with regard to theirfluid, for automatic adjustment of the angular position of the liftingblade, under the influence of the nosewheel of the aircraft transported,when cornering. In the event of a loss of fluid as a result of leakagein the hydraulic system or a rupture of a hydraulic hose, a suddenlowering of the lifting blade may disadvantageously take place withprobable damage to the nosewheel or its suspension on the aircraft.Furthermore, it is complicated to use two upper longitudinal couplingrods whose directions of action have to intersect on the imaginarylongitudinal axis at a point forming a pendulum point of the blade.

In comparison thereto, the object on which the invention is based is toprovide a towing vehicle of the construction mentioned at the beginning,which allows upper longitudinal coupling rods to be dispensed with, andin which any leakage in the fluid supply can no longer have theconsequences mentioned for the two fluid piston-cylinder units.

According to the invention, this object is achieved in the towingvehicle mentioned at the beginning, in that the lifting blade is coupledso as to be pivotable in all directions by means of a ball joint whichis fastened to the chassis of the towing vehicle and acts centrally onthe back of the lifting blade, and in that at least one fluidpiston-cylinder unit, acting on the lifting blade above or below theball joint at distance from the latter, can be locked and released in aposition which raises the lifting blade.

The use of a ball joint instead of two specifically arrange longitudinalcoupling rods leads to a particularly simple and sturdy, uncomplicatedconstruction which nevertheless guarantees the required degree offreedom of the lifting blade. In this case, although the lifting bladecan no longer be raised as a whole, this is not even necessary; it isalready sufficient for the fluid piston-cylinder unit to tilt thelifting blade when it is acted upon by pressurized fluid, the lowerregion of the lifting blade rising, as a result of which the nosewheelresting on it is also raised. The lifting blade is thus tilted in thiscase about a transverse axis passing through the center-point of theball joint.

Since the at least one fluid piston-cylinder unit is mechanically lockedafter it has tilted the lifting blade up, it then acts as a coupling rodwhich, on the one hand, supports the lifting blade against tilting downunder load and, on the other hand, forms a guide by means of itsball-joint bearing constructed at one end on the chassis and at theother end on the lifting blade when, during cornering, the nosewheelforces the lifting blade to be set obliquely or to pivot about animaginary longitudinal axis passing through the center-point of the balljoint holding the lifting blade centrally at the top. If there is only asingle fluid piston-cylinder unit which acts centrally on the liftingblade above or below the ball joint, there is additionally a laterallongitudinal coupling rod which prevents any pivoting of the liftingblade about the vertical axis which would otherwise be possible.

According to a preferred embodiment, two fluid piston-cylinder units areprovided, which are arranged symmetrically relative to one another andare coupled to the lifting blade 8 below the ball joint 25 which acts inthe upper region of the lifting blade 8 (FIGS. 1-7).

The invention is explained in greater detail below with reference to anexemplary embodiment illustrated in the drawing, in which:

FIG. 1 shows an illustrative view of the towing vehicle according to theinvention obliquely from the front and from the top with the grippingand drawing-in device pivoted in;

FIG. 2 shows a plan view of the towing vehicle according to FIG. 1 withdifferent positions of the gripping and drawing-in device on an enlargedscale;

FIG. 3 shows a section on the line A--A in FIG. 2 to illustrate detailsof the gripping and drawing-in device on a further enlarged scale;

FIG. 4 shows a side view of the lifting blade in the direction of thearrow B in FIG. 2 with the gripping and drawing-in device in the openposition, and of the suspension of the lifting blade on the chassis ofthe towing vehicle;

FIG. 5 shows a side view corresponding to FIG. 4 with the gripping anddrawing-in device closed and with a nosewheel, illustrated by dot/dashlines, gripped between the lifting blade and the gripping and drawing-indevice;

FIG. 6 shows a side view corresponding to FIGS. 4 and 5 with the liftingblade pivoted up in addition to the gripping and drawing-in device withthe nosewheel raised due to the upward tilting;

FIG. 7 shows a rear view in the direction of the arrow G in FIG. 6 toillustrate the lifting blade and gripping and drawing-in device in aposition gripping a double nosewheel, holding the latter raised, and inan oblique position during cornering;

FIG. 8 shows a plan view corresponding to FIG. 2 of a second embodiment;and

FIG. 9 shows a side view corresponding to FIG. 6 of the secondembodiment according to FIG. 8.

According to FIG. 1, the towing vehicle 1 shown has a driver's cab 2with a turning seat 3 and two steering devices 4, so that the driver isalways able to steer in the direction of travel regardless of whethertravel is respectively forwards or backwards. The chassis 5 of thistowing vehicle 1 has a fork-like receiving area 7 between the wheels 6of one axle which are suspended independently of one another, in whichreceiving area there is arranged a retractable and extensible grippingand drawing-in device 9 which is fastened to a lifting blade 8 and bymeans of which the nosewheel 10 of an aircraft 11 can be gripped (FIGS.1 and 4). During the gripping of the nosewheel 10, the latter can bedrawn onto the lifting blade 8 which is pivotable relative to thechassis 5 both about a transverse axis 14 and, for matching to obliquepositions of a nosewheel 10 which as been accommodated, about alongitudinal axis 13. The pivoting of the lifting blade 8 takes place bymeans of two fluid piston-cylinder units 12 arranged symmetricallyrelative to one another between the chassis 5 and the lifting blade 8.As shown particularly clearly in FIGS. 4 and 5, the lifting blade 8 isof angled design in cross-section, specifically with a run-up ramp 15,which can be lowered down to the ground, a supporting wall 16 and aholding-down wall 17. As can be seen from FIG. 2, the lifting blade isreinforced laterally to form abutments 18, at which the fluidpiston-cylinder units 12 are coupled to the chassis 5 on the piston sidevia axle bearing 19 and on the cylinder side via axle bearing 20.

Fastened to one side of the lifting blade 8 (this side is illustrated atthe top in the plan view according to FIG. 2) is an angular link 39 forthe controlled guiding of a bent lever 21 which is retractable andextensible by means of a piston-cylinder unit 22 in the direction of thedouble arrow D (FIG. 2) and additionally is also pivotable in thedirection of the double arrow E. Together these elements form thegripping and drawing-in device 9 for the nosewheel 10, which can be seenin FIG. 4 and 5, of an aircraft 11 which is indicated with its lowercontour in dot/dash lines in FIG. 4. The associated nose-wheel supportis indicated at 23, and the open cover of the landing-gear shaft at 24.

According to the invention, the lifting blade 8 is coupled so as to bepivotable in all directions by means of a ball joint 25 which isfastened to the chassis 5 of the towing vehicle 1 and acts centrally onthe back of the lifting blade 8, in the preferred embodiment shown inits upper region (FIGS. 2 and 4). The ball joint is fastened to thechassis 5 by a bearing mount 26 and to the rear wall of the liftingblade by a bearing mount 27 arranged there.

The method of operation is as follows:

The towing vehicle 1, with the gripping and drawing-in device 9 in theopen position illustrated in FIG. 2, moves in the direction of the arrowI towards the aircraft 11 until the nosewheel 10 is in the positionillustrated in FIG. 4 in contact with the run up ramp 15 of the liftingblade 8. The path of the nosewheel in the direction of the arrow C intothe fork-like receiving area 7 is made possible by the bent lever 21 inits position illustrated by solid lines in FIG. 2 by the fact that thebent lever is located in a correspondingly angular recess 37 in thecantilever arm 38, into which recess it can be pivoted with the aid ofthe piston-cylinder unit 22. In this case, the angular link guide 39forms restricted guidance in which the bent lever 21 can then be pivotedback again in order to come to rest against the nosewheel 10 by means oftriple rollers 28. In this case, the bent lever 21 is illustrated bydot/dash lines in various different positions or settings in FIG. 2which it can assume infinitely variably when being pivoted in and out.As soon as the triple rollers 28 have come to rest against the nosewheel10, during further retraction of the piston-cylinder unit 22 thenosewheel 10 can be pushed up the run-up ramp 15 up to the stop on thesupporting wall 16. At this point it should be noted that the exemplaryembodiment shown is provided for double nosewheels 10 as shown by thepresence of two sets of triple rollers 28 which rest in each caseagainst one tire of the double nosewheel 10. The indentation 29 in thebent lever serves to allow space for the crossbar (not shown) of thenosewheel 10.

A preferred type of link guide can be seen, in particular, in FIG. 2 andthe sectional view in FIG. 3. Accordingly, two upper and lower rollers30 located coaxially one above the other are provided in each case onthe bent lever 21 and are guided by the upper and lower rails 31 of thelink 39. As can be seen, the link guide 39 on the one hand and the bentlever 21 on the other hand form angles which open in opposite directionsto one another, preferably right angles. It is obvious that a secondgripping and drawing-in device of the type described could be locatedsymmetrically on the other side of the lifting blade 8, the bent levers21 naturally only being allowed to extend at the maximum up to thelongitudinal center-plane 13.

From the position of the lifting blade 8 with its gripping anddrawing-in device 9 shown in FIG. 5, the said lifting blade is thenpivoted up in the direction of the double arrow F by actuating the fluidpiston-cylinder units 12 in such a way that the nosewheel 10 and thusthe aircraft 11 are raised correspondingly.

According to the invention, the two fluid piston-cylinder units 12 cannow be mechanically locked in the extended position shown in FIG. 6raising the lifting blade 8, which is not shown in detail. This avoidsany abrupt lowering of the lifting blade in the event of a suddenpressure drop in the hydraulic system for whatever reason with adverseconsequences both for the aircraft on the one hand and for the towingvehicle itself on the other hand.

FIG. 7 shows a detail from a rear view in the direction of the arrow Gin FIG. 6 during cornering of the vehicle 1, specifically towards theleft with a double nosewheel 10 which has been accommodated. Owing tothe mechanical locking, as mentioned, the units 12 take on the functionof longitudinal steering means which are of fixed length, which requiresaxle bearings 19 and 20 (FIG. 2) in the form of ball joints. FIG. 7shows how the units 12 follow in the event of a deflection (shown herein the direction of the arrow H), in the case of deflection in theopposite direction naturally in a reversed direction accordingly. Theguidance takes place, of course, by means of the double nosewheel 10, inwhich case it is clear that, without a nosewheel, for example whenmoving the towing vehicle according to FIG. 1 to an aircraft to be towedor away from an aircraft which has already been towed, back and forthpivoting of the blade 8 with the gripping and drawing-in device 9 couldtake place if there were not a supporting coupling rod 36 present in theform of a piston-cylinder unit (FIGS. 2 and 7) which, as a type ofcrossbar, ensures stability of the arrangement, as long as the towingvehicle is not loaded, as mentioned. After the nosewheel 10 has beenloaded and has taken over the guidance, the piston-cylinder unit 36 isnaturally relieved of pressure in order to be able to follow everymovement of the arrangement brought about by the nosewheel 10. Thecoupling, at one end to the chassis 5 at 32 and at the other end to theblade 8 at 33, can be seen particularly clearly in FIG. 2.

The coupling of the piston-cylinder unit 22, at one end to the link 39at 34 and at the other end to the bent lever 21 at 35, is shown in thesame Figure. Instead of being coupled to the link 39, such coupling tothe lifting blade 8 is also possible.

In the second embodiment illustrated in FIGS. 8 and 9, the same partsare given the same reference numerals in each case compared to the firstembodiment.

The difference from the first embodiment consists mainly in the factthat here the ball joint 25 is provided in the lower region of thelifting blade and the fastening of the ball joint 25 to the chassis 5 islocated correspondingly lower, whereas the fluid piston-cylinder unit12, specifically here only a single unit of this type, engages on theholding-down wall 17 and thus in the upper region of the lifting blade8, consequently above the ball joint 25. It is obvious that more or lessthe same kinematic effect of the lifting blade thus results when it istilted about the transverse axis 14 running through the ball joint 25,but the fact must not be overlooked that the different engagement of theball joint 25 on the lifting blade 8 results in different raising pathsor distances of the run-up ramp 15 from the ground up to the raisedpositions shown in FIGS. 6 and 9. Assuming the same angle of tilt, agreater distance of the run-up ramp 15 of the lifting blade 8 from theground naturally results in the firstmentioned embodiment according toFIGS. 1 to 7 than in the case of the second embodiment according toFIGS. 8 and 9. This is due quite simply to the greater distance of therun-up ramp 15 from the ball joint 25 in the first embodiment comparedto the said distance in the second embodiment.

In order now to increase this distance, as shown in FIG. 9, a support 44which bears the ball joint 25 can be arranged in the lower region of thelifting blade 8, preferably in the region of the crease edge 43 betweenthe run-ramp 15 and the supporting wall 16. The greater the distance isbetween the lifting blade 8 and the ball joint 25, i.e. the more thetilting of the lifting blade 8 in the direction of the double arrow Fbecomes a pivoting motion, the greater the distance a between the groundand the lower edge of the run-up ramp 15 can become.

At this point, it should be noted that, even in the first embodiment,there is already a distance b (FIG. 4) between the supporting wall 16and the ball joint 25. However, as mentioned, this distance is ofparticular importance in the embodiment according to FIGS. 8 and 9.

This embodiment is consequently advantageous because it has only asingle fluid piston-cylinder unit 12 to move the lifting blade. This isarranged expediently in a vertical longitudinal center-plane 13 which iscommon to the ball joint 25, in this case above the ball joint 25.Furthermore, at least one longitudinal coupling rod 40 providedlaterally at a distance c from the ball joint 25 is coupled at one endvia a first bearing 41 to the chassis 5 and, at the other end, via asecond bearing 42 to the lifting blade 8. Since the second bearing 42 isexpediently seated on the transverse axis 14 of the lifting blade 8running through the ball joint 25, no lateral deflecting about thevertical axis can occur at all. In order also to prevent raising orlowering of the one side of the lifting blade 8 in relation to the otherwhich would otherwise be possible, a fluid piston-cylinder unit forminga supporting steering means 36 in the angled state is again coupled atone end to the chassis 5 and at the other end to the lifting blade 8.Since this supporting steering means is intended precisely to preventany lowering or raising of one side of the lifting blade 8, it isexpediently installed at least approximately vertically, as can be seenin FIG. 9. In order to be able to fulfill its function, the supportingsteering means 36 must naturally likewise have a lateral distance d(FIG. 8) from the ball joint 25.

I claim:
 1. Towing vehicle for maneuvering aircraft without a towbar,the chassis (5) of which vehicle has a fork-like receiving area betweenthe wheels of a coaxial wheel suspension, in which receiving area thereis arranged a retractable and extensible gripping and drawing-in devicewhich is fastened to a lifting blade and by means of which the nosewheelof an aircraft can be gripped and drawn onto the lifting blade which ispivotable relative to the chassis both about a transverse axis and, formatching to oblique positions of a nosewheel which has been received,about a longitudinal axis by means of two fluid piston-cylinder unitsarranged symmetrically relative to one another between the chassis andthe lifting blade, characterized in that the lifting blade is coupled soas to be pivotable in all directions by means of a ball joint which isfastened to the chassis of the towing vehicle and acts centrally on theback of the lifting blade, and in that at least one fluidpiston-cylinder unit, acting on the lifting blade above or below theball joint at a distance from the latter, can be locked and released ina position which raises the lifting blade.
 2. Towing vehicle accordingto claim 1, characterized in that two fluid piston-cylinder units areprovided, which are arranged symmetrically relative to one another andare coupled to the lifting blade below the ball joint which acts in theupper region of the lifting blade.
 3. Towing vehicle according to claim1, characterized in that, if only a single fluid piston-cylinder unit isarranged above or below the ball joint in a vertical longitudinalcenter-plane which is common to the ball joint, at least onelongitudinal steering means, provided laterally at a distance from theball joint, is coupled at one end via a first bearing to the chassisand, at the other end, via a second bearing to the lifting blade. 4.Towing vehicle according to claim 3, characterized in that the secondbearing is seated on the transverse axis of the lifting blade runningthrough the ball joint.
 5. Towing vehicle according to one of thepreceding claims, characterized in that a fluid piston-cylinder unitforming a supporting steering means in the locked state is coupled atone end to the chassis and at the other end to the lifting blade. 6.Towing vehicle (1) for maneuvering aircraft (11) without a towbar, thechassis (5) of which vehicle has a fork-like receiving area (7) betweenwheels (6) of a coaxial wheel suspension, in which receiving area thereis arranged a retractable and extensible gripping and drawing-in device(9) which is fastened to a lifting blade (8) and by means of which anosewheel (10) of an aircraft (11) can be gripped and drawn onto thelifting blade (8), characterized in that the gripping and drawing-indevice (9) fastened to the lifting blade (8) comprising at least oneangular link guide (39), arranged on one side of the lifting blade (8),and a bent lever (21) which is controlled by the said link guide and, togrip the nose-wheel (10), can be pivoted by means of a piston-cylinderunit (22) into the free region of the fork-like receiving area (7) takenup by the nosewheel and, to release the nosewheel, can be pivoted out ofthe said region again, the link guide and the bent lever forming angleswhich open in opposite directions to one another, and that at eachcantilever arm (38) correlated to a link guide (39) a respectiveangularly shaped recess (37) is provided into which the bent lever (21)can pivot so that the pivot angle between gripping and releasingpositions is less than 90°.
 7. Towing vehicle (1) for maneuveringaircraft (11) without a towbar, the chassis (5) of which vehicle has afork-like receiving area (7) between wheels (6) of a coaxial wheelsuspension, in which receiving area there is arranged a retractable andextensible gripping and drawing-in device (9) which is fastened to alifting blade (8) and by means of which a nosewheel (10) of an aircraft(11) can be gripped and drawn onto the lifting blade (8) which ispivotable relative to the chassis (5) both about a transverse axis and,for matching to oblique positions of the nosewheel (10) which has beenreceived, about a longitudinal axis by means of two fluidpiston-cylinder units (12) arranged symmetrically relative to oneanother between the chassis (5) and the lifting blade (8), characterizedin that the lifting blade (8) is coupled so as to be pivotable in alldirections by means of a ball joint (25) which is fastened to thechassis (5) of the towing vehicle (1) and acts centrally on the back ofthe lifting blade (8), and in that at least one fluid piston-cylinderunit (12), acting on the lifting blade (8) above or below the ball joint(25) at a distance from the latter, can be locked and released in aposition which raises the lifting blade (8), in that the gripping anddrawing-in device (9) fastened to the lifting blade (8) comprises atleast one angular guide (39), arranged on one side of the lifting blade(8), and a bent lever (21) which is controlled by the said link guideand, to grip a nose-wheel (10), can be pivoted by means of apiston-cylinder unit (22) into the free region of the fork-likereceiving area (7) taken up by the nosewheel and, to release thenosewheel, can be pivoted out to the said region again, the link guideand the bent lever forming angles which open in opposite directions toone another, and that at each cantilever arm (38) correlated to a linkguide (39) a respective angularly shaped recess (37) is provided intowhich the bent lever (21) can pivot so that the pivot angle betweengripping and releasing positions is less than 90°.
 8. Towing vehicle (1)according to claim 6 or 7, characterized in that the angularly shapedrecess (37) is arranged in a cantilever arm (38) substantially in frontof the axle of wheels (6).
 9. Towing vehicle (1) according to claim 6 or7, characterized in that the free end (21') of the bent lever (21) hasat least one roller (28) for contact with the nosewheel (10).